Two cycle internal combustion engines are commonly provided with transfer passages and porting providing for delivery of fuel from the crankcase into the combustion chamber above the piston. Intake porting is provided in order to introduce fuel into the crankcase space for compression therein upon the downward stroke of the piston and for delivery from the crankcase space through the transfer passage means. Intake valves are commonly provided in the intake passageway or intake tract.
The present invention is concerned with improvements in passage and porting arrangements both in the transfer and in the intake systems providing for increase in delivery of fuel into the combustion chamber above the piston. The increase in fuel delivery and the consequent improvement in operation of the engine are accomplished according to the present invention by providing a novel interrelationship between the intake porting and passages and the transfer porting and passages, according to which the intake porting and passages not only deliver the fuel to the crankcase space, but also deliver fuel by an injector type of action into the transfer fuel flow during the phase of the cycle of operation in which fuel is being transferred from the crankcase to the combustion chamber.
In the arrangements according to the present invention, reed type intake valves are preferably provided in the intake tract, and injector porting or passages are provided in order to deliver fuel from the intake tract substantially directly into the transfer passage means. According to the invention, this may be accomplished in several ways by providing a region of at least one transfer passage intermediate its ends in communication with the intake passage or tract downstream of the valve means. Indeed, in certain arrangements according to the invention, a region of the intake tract downstream of the valve means and a region of at least one transfer passage intermediate its ends are common to each other.
Still further, according to the invention provision is made for increased fuel input by the employment of a novel form of passage means interconnecting the intake tract and the transfer passages and ports close to the point of fuel delivery into the cylinder. Moreover, this is accomplished in accordance with the present invention in a manner which not only increases the intake of fuel but which also enhances the scavenging of the combustion gases from the cylinder under the influence of the incoming fuel.
Several embodiments of engines providing improved operation in various aspects as referred to above are illustrated in the accompanying drawings and described hereinafter.